1. Field of the Invention
The present invention relates to a spindle driving assembly, and, more particularly, to a high speed system for use in a spindle driving assembly in a pick and place machine.
2. Description of the Related Art
The present invention relates primarily, although not exclusively, to machines known in the electronics assembly industry as pick and place machines. In a pick and place machine, a spindle mounted on a spindle assembly is brought into contact with a die or other electronic component in order to pick up the die or component. The spindle assembly is then moved to another location, where the die or component picked up by the spindle is then placed in an appropriate location for assembly.
In conventional pick and place machines, one type of spindle assembly utilizes a vacuum spindle. A vacuum spindle includes a nozzle at a tip at a lower end of the spindle. A vacuum is applied to the nozzle at the tip of the spindle in order to enable the spindle to pick up a die or component. The spindle is then moved to an appropriate location for placing the die or component. In order to detach the die or component from the spindle, a pulse of air, sometimes referred to as an air kiss, is applied to the nozzle in order to blow the die or component away from the tip of the spindle.
In conventional pick and place machines, the vacuum is created by applying pressurized air to a venturi, which in turn, creates a vacuum. The vacuum is then directed to the spindle for picking up components. In addition, in order to discharge the die or component, the pressurized air was also applied directly to the tip of the nozzle.
A conventional pick and place machine may have a pick and place head that includes a plurality of spindle assemblies in order to maximize assembly time. However, the conventional valve assemblies used in conjunction with a respective spindle assembly were relatively large. Accordingly, in order to fit as many spindle assemblies as possible in the pertinent portion of the pick and place head, the valve assembly was located remotely from the spindle assembly. A disadvantage of locating the valve assembly remotely from the spindle assembly is that the time required for a vacuum applied at the venturi to reach the tip of the nozzle added to the processing time of the pick and place machine.
Some conventional valve assemblies used in a pick and place head had an actuating time of approximately 4.5 milliseconds. Accordingly, in a conventional pick and place machine, when the actuating time is factored together with the distance that the valve assembly is located from the spindle assembly, the time for the vacuum to reach the required level, typically about 20 inches of mercury, is about 40 milliseconds.
In other conventional assemblies, the valves are mounted on the spindle head frame, but are connected to the spindles with tubes. Such an arrangement is difficult to assemble.
Accordingly, it is an object of the present invention to provide a pick and place head for a pick and place machine, wherein the actuating time can be reduced.
It is a further object of the present invention to provide a spindle assembly for a pick and place machine, wherein the valve assembly is small enough so that it can be located adjacent the spindle in order to minimize the time required for the vacuum for air pressure to be applied to the nozzle tip.
It is still another object of the present invention to provide a valve assembly for a pick and place machine, wherein the actuating time of the valve can be reduced in order to minimize processing time.
According to one embodiment of the present invention, a spindle assembly for a component pick and place machine comprises a housing containing a spindle for movement therein along a longitudinal axis of the spindle; the housing accommodating a valve for controlling the flow of air to an inner bore of the spindle; the inner bore of the spindle having an opening at one end for communicating the flow of air for picking and placing the components; and the flow of air from the valve to the inner bore of the spindle is internal to the housing through passageways.